AC Circuit

Given an RL charging circuit with battery voltage, $\epsilon$ = 30 V, an inductor with L = 30 mH, and a resistor of 50 $\Omega$, how long will it take for the current to reach 75% of its maximum value?

In the circuit below, the switch sw has been open for a long time. At t = 0, the switch closes. Write, as a function of time for t > 0:

B. the energy in the inductor

A 50 $\mu$F capacitor is charged to 12V and then connected across a 60 mH inductor. What is the maximum current that will flow in the circuit?

A LC circuit consists of a 10 mH inductor and a 1 microfarad capacitor. If the maximum instantaneous current is 0.1 A, what is the greatest potential difference across the capacitor?